Variable-speed transmission



March 13, 1928.

R. H. PRATT 1662164 VARIABLE SPEED TRANSMSSION lFiled July 26. 1926 4Sheets-Sheet l 1U Ellnui" lmlllllillun A cu rrllululnillllililiiillmlllmH1 n l d llmllumnnui annuals v flirlullmu Mar-c1113, 1928.

1,662,164 RT H. PRATT VARIABLE SPEED TRANSMISSION Filed July 26. 1926 4Sheets-Sheet 2 11X 9X 1o my S 4Q 110' y l Iw 9 10b 5 N i 1- lD hwmvm:

Rass HDRMT.

R. H. PRATT VARIABLE SPEED TEANsMlssIoN March 13, 1928. F 1,662,164

Filed July 26. 1926 4 s heets-snet 5 4 K 14C K 14u 14D 1 14d n 14dlNvENroR March 13, 1928.

1,662,164 R. H. PRATT VARIABLE SPEED TRANSMISSION Filed July 26. 192s 4sheets-sheet 4 .l NVeN'ron:

`Rass HRATT.

Patented Mar. 13, 1928.

Ross H. PRATT, or WASHINGTON, nrs'rnrorron COLUMBIA.

VARIABLE-SPEED TRANsMrssroN;

Application filed July 26,

rl`his invention relates to variable speed transmissions and moreparticularly to variable speed gearing especially designed for use inconnection with the transmissions ot' motor vehicles.

It is a major purpose of the present invention to provide a transmissionwherein variation oit speed is had through operatively engaging gears ofvarying speed ratios by means ot' specially controlled clutches, theteeth of the gears heilig constantly engaged or in mesh.

lt is a further object of the present invention to provide an improvedtransmission wherein acceleration or deceleration ot speed. may heconveniently had, and wherein, it' desired, the change may be readilymade from a high to a lower gear for the purpose oit utilizing' theengine as a braking power when descending grades. It is a still furtherpurpose of the present invention to provide an improved transmissionwherein a change to a slow speed is made easy when traffic conditionsrequire the same, Without cutting oli the fuel supply or otherwise re-yducing the pulling power of the engine or ovcrburdening the engine byexcessive application ot' brakes, the lower speed yor gear giving theengine greater leverage and eliminating the danger of stalling onrailway or streetlcar tracks or other dangerous places when drivingslowly. A 1

Vln the general type ot so called sliding gear transmissions, wherein agear must be brought from a position at rest into engagement withanother gear through a sliding movement, it is diihcult and oftenimpossible to dieetsuch engagement when the speed ot rotatioii of thepropeller shaft is greater than the speed of rotation of thecrank shaft,wh ich is generally the condition when the vehicle is descending agrade. Accordingly with the aforesaid sliding gear type of transmissionit becomes dangerous and in most instances impossible to attempt such ashifting of gears to utilize the brakingl pOwer ot the engine at a lowerspeed. In the present invention, with all ot the gears constantly inmesh. any desired change or variation from high gear to a lower gear orvice versa may he conveniently had.

t is a still further object of the present invention to provide in atransmission of the tvpe set forth, means for automatically shitting theusual clutch between the engine 1926. Serial N0. 124,895.

andI drive shafts when ka change in gearing` is desired, withoutthenecessity ot' operating the usual clutch pedal.

It is a still further object ofV the present invent-ion to providemechanism including a lever, whereby the various changes in' gear'- ingmay be had in proper sequence hy a cou-V t-.inuous movement of suchlever in one di# y rection.

',lransiuissions have heretofore heen` designed having all gearsconstantly in mesh, engagement being had'between desired gears forvarying speeds by `means o'li slidahle keys engaging the hubs'oi` thegears or by equivalent means. These `transmissions as a class havefailed ot heing sllocess'ul first `because ot the stress applied to thekeys and second because oi' the difficulty of properly shitting the keysunder the varying conditions oi? relative speed hetween the Vvehicle andthe 'murine` The present invention is designed mechanism,

to operrte Q through Vproper clutches which form an integral/part ofeach driven gear, the operative mechanism being so designed as tosimultaneously disengage the engine clutch coincid' t with theLtransition rroin one speed to an ther. Further objects ot the presentinvent-ion will he hereina iter more fully set forth.

The accompanying drawings illustrate one practical transmissionembodying the invention which will be described in detail toenahleothers to understand andnse the saine.` but the invention not consideredrestricted to the speciic construction n shown in the drawings, andreference is therefore had to the claims tor summaries ot the essentialsoi 'the invention andot f the novel features ot construction and ot thenovel combinations ot parts for all of which protection is desired.

As shown in the drawings: H Figure lis a top plan view ot the entiretransmission, parts being broken away.

Figure is ,a detail view illustrating several ofthe gears, clutches, andoperative cams, parts being shown in section. Figure 3 is a detailsectional viewthrough one'ot the gears, its associated clutch andoperative cam therefor, illustrating the cani in engaged position. y nFigure L is a detail section-al View takenon the line 46-4 of Figure 2.Figure 5 is a detail sectional view taken on the line 5 5 of. Figure 2.

Figure 6 isa detail sectional view taken on the line (36 of Figure 1,illustrating the gear shitting lever and guide therefor.

Figure 7 is a detail sectional view taken on the line 7 7 of Figure (3,illustrating the gear shifting lever guide bracket.

Figure S is a detail sectional view tahen on the line S-S of Figure C.

Figure E) is an enlarged detail seetional view taken on the line 9-9 ofFigure (i,

Figure 10 is a detail sectional view taken on the line 10-10 ofFigure 1. illustrating the cam for shifting or Controlling lirst: or lowgear.

Figure 11. is a detail sectional view taken ou the line 11-11 ol"Figure 1. illutating the eam for controlling second or intermediategear.

Figure 12 is a detail Sectional view taken on the line 12)-12 ot Figure1, illustrating the 'am for controlling third or high gear,

Figure 13 is a detail sectional view talten on the line 13 13 otl Figurel, illustrating the eam for Controlling reverse gear.

Figure 1l is a detail sectional view taken on the line. 14-14 ot Figurel, illustrating the eam for controlling the rotation ot ther drivenshaft, by the drive shaft through a counter shaft, for all speedsincluding reverse exeept high.

Figure l5 is a detail sectional view taken on the line lf3-15 of Figure1, illustratinp|` the :am for controlling the automatic shifts ing orope xation oi" the engine clutch, be tween the engine and the driveshafts.

As shown in the drawings and as is usual in motor vehieletrims-missions. tht` engine shaft E inieratively connected with thedrive :shaft FS through the medium ot the usual type of cone of diseelnteh C. ',l`he shalt ti is preferably square in rross seetion 'l'or apurpose to be hereinafter more tully deferibed. and has properlypositioned thereon a sleeve 1 in on which is slidably mount ed for lreilrotation a gear l adapted to mesh with a gear L' rigidly seeured upon aeonuter shaft i jonrnaled in suitable bearings ,l-f and i. in thetransmission housing J.. 'l`o provirhl tor 'l'ree rotation ot' the drivesha'l't. sleeves or rings 5 and 5 are mounted therron adapted to roatewithin bearings -l'2 and i1 in the transmission houing.

Keyed or otherwise rigidly secured to the ennnt'er sh: l't 3 are aplurality ot' pinions or gears t, T and the gears t3 and T mesh ingdirectly with gears t) and 10 upon a driven shaft; D, while the gear Smeshes with a gear 11 also mounted upon the driven shalt through anintermediate gear 1Q mounted upon a etub shaft 1Q:L properly positionedin suitable bearings within the transmiesion housing. The gears 9, lt)and 11 respectively control lon', intermediate and reverse speeds of thetianfszmission, and are slidahly mounted for free rotation upon sleevesD 10l and 1' respectively, the eleves being properly positioned upon thedriven shaft l). The shaft l) is prete 'ably square in eross .seetionand of a diameter equal to that ot the drive shaft S. To provide forfree rotation ol' the driven shat't l). a sleeve journaled in a bearing1" in the transmission housing. is mounted thereon.

lt will thus; he .seen that the driven shaft l) is operatively eonneetedand driven by thil drive shaft S through the g -ars 1 and i2 for low`intermediate and reverse speeds. lt is customary in motor vehicletransmissions in general use. that the running or high speed of thetransmission b a direet drive trom the engine shalt. and to this end aslidahle eluteh 12. ol any desired type. is splined or otherwiseslidahly secured upon a sleeve 125 positioned upon the driven shaft l)adjacent the extremity thereof. the shafts l) and S ter minating withinthe huh of the eomplementY al stationary portion lill ol the eluteh.'l`he gear 1 is provided with a similar elnteh l" whieh is disengagedwhen it is desired that the high speed or directl drive he used. lt willhe readily understood that when :sneh rluteh is disengaged and the highgear or direct drive is being used. all ot the gears will be in mesh andwill be at rest. the said gears: in no way interfering with th:l direetdriving or' the driven shaft: l) hy the drive .shaft H, inasmurh as thesaid shat'r` are tri-e to rotate through the medium ol the slee-res uponwhieh the said gears artI mounted.

The gears i), 10, 11 and l` it will be noted are positioned in .slightlyoil'set relationship to the gears with which they mesh so that they maybe moved in a right hand dirertiou (see Figure 1) into engaging positionand will more fully mesh with their eompanion gears. this otlisetrelationship. it will be noted however. is not sullieient to interl'l-rewith the proper meshing or engaging ol all gears aty all tunes.

'l`he inner l'aee of the gear 1 is provided with a plurality o'l t-lutehteeth adapted lo engage with opposilely direeted teeth upon a stationaryeluteh member i rigidly .seenred upon the drive shaft S in apar-edrelationship to the gear fl; the said gear thus hei-online' the movablehall ol a slidably operated eluteh. ln like manner the inner lat-es: ot'the gears t). 1,() and 11 and oi' the rlutrh .lil are each provided witha plurality ol clutch teeth adapted to engage with oppositely directedelnteh teeth upon stationary cluteh men'ibers Sil'. 1d". i1". and 125respeetively.

lt will thus be seen that with the gear l in the position as illustratedin Figure l. the eluteh 1f' is disengaged and upon the rotation of thedrive shafty S the sleeve l will turn freely within the gear l and nomotion will he impartial to the eountershaft- 3. Movement of the gear 1,in a right hand direction will result in the teeth therewhich, beingrigidly secured to the shaft S rotates therewith, and such engagementwill result in the rotation of the gear 1 and through Vthe gear 2 therotation of the countershaft, and through the gears 6, 7k

and 8, the rotation of the gears 9, 10 and 11 will result. It will beclearly understood that engagement of the proper clutch 91, 10b or 11bwill then result in the operatingr or driving of the driven shaft at lowspeed or gear, intermediate gear or reverse gear respectively. If it isdesired to drive directly at high speed or gear, disengagement of theclutch 1b will permit all of the gears to come tol rest their clutcheshaving also been disengaged, while engagement of the clutch 13b will, asabove described, permit of a direct drive of the shalt D through theshaft S. It will be understood that any desired form of clutch may beused, that shown being illustrative. rather than limitive. will befurther understood that while the transmission has been illustrated anddescribed as including three speeds forward and one speed in reverse, byincreasing the number of gears upon the countcrshaft and upon the drivenshaft, and in like manner increasing the operative control mechanism,the number of variations of speed either forward 0r backward may beincreased at will.

. lVhile the shafts D andY S have been described as being preferablysquare in cross section and the gears and clutch being slidably mountedfor free rotation upon sleeves properly positioned upon thesaid shafts,shafts of any desired cross-sectional shape might be as convenientlyused and any desired means be Vemployed to permit of the free rotationland slidable movement of the said gears; or clutches upon the saidshafts.

Suitable mechanism is provided to insure the proper engagement of thedesired clutch at the desired time, and to insure the disengageijnent ofall clutches except the ones governing the desired speed. rllhismechanism, inthe preferred embodiment of the present invention,comprises a cam shaft K upon which are rigid-ly secured a series of cams9x, 10X, 3X, 11x, 1X and CX. These cams are preferably disc-like and areprovided with offset portions properly positioned along the peripheriesthereof; the cams. being so positioned along the cam shaft 'K that theirperipheries Will engage bet-Ween shoulders formed upon the hubs ofthegears 9 and 1f), the clutch 13, the gears 11 and 1, and the clutch C. Inthe neutral position of the transmission as illustrated in Figure 1,each of'these cams presentsv a non-offset portion to its respective'gearyor clutch, thus securely retaining the slidable` portion of each clutchin extreme left or disengaged position. 'it will be noted that theoffset portions of the cams 9X, 10S-131,111, and 1X project in` a di-`notch in the guide bracket 15.

rection'to the right (see Figure 1), with the result that rotation ofthe cani shaft to 'pros duce engagement between the offset portion ofany cam and its associated clutch member will move such slidable clutchmember in a direction to the right, with the resultant positiveenga-gement of the particular clutch.

Any desired means may be provided for the proper rotation of the camshaft Preferably such means comprises a gear shift lever lli having ahub portion 14s rigidly secured to a stub shaft 141 journaled withinsuitable bearings in the transmissiony housing` Secured to the stubshaft 14h, or as disclosed in the drawings, forming an integra-l part ofthe hub lele, is a toothed segment 14C ad aptcd to engage with a pinionlil1 rigidly secured to the cam shaft l.' Movement of the lever 14 ineither direction will result in the rotation of the stub shaft 149) andthrough the segment lllc and the pinion leid rotation of the cam .sha-ftwill result. The lever 14 projects upward through' a suitable slot 4g inthe cover 4f of the 'transmission housing; a cover ll, or any othersuitable, means being provided for the vexcl sion of dust or foreignmatter.

Mounted upon any suitable place as the dash or instrument board of thevehicle a bracket or guide 15 provided with a slot'y l' 15 in which thelever 14 is guided. This slot may be provided along one side thereof,

with. a plurality of `cut-away portions or notches properly marked, asindicated in Figure 7 of kthe drawings, with the indicia R, N, 1, 2 fand3 for the reverse, neutra-l, first or low, second or intermediate, andthird or high speeds respectively. 1With the lever Il in the neutralposition the. rotation of the driven shaft l) may be iutceleratedthrough all ofits' speeds from low to high by a movement of the lever inone direction from said position, while nioveinei'it of the lever in thereverse direction willV result in the enga-gement of the reverse speed.`Any desired'nlfe-.ins may be provided to insure the proper seatingofthe lever in any desired Pre fe rah ly lli?) the lever is recessed onits side opposite the f notches in theV guide brochet and is adapted to`receive a pin he held in engagement with Y the adjacent side the slot15: by the spring` letf seated within the recess. A slight pressureagainst the lever will be sufficient to disengage the same andwillperiuit ofthe shifting thereof to any desired notch intheguidebraclret, while the tension of the coil spring 14f is sui'licienttoinsure' the lever remaining' in any desired notch until manuallyremoved therefrom.

i A movement of the leverfrom the neutral position or notch fhnf to theVlow speed position or'notch l, will result in the partial rotation ofthe stub shaft 14h in the directionxof the arroav,'see.Figure 6, andthrough CFI " the clutch ll'.

the segment 14C and pinion 14; the cam shaft K will be rotatedsutiiciently to engage the ottset portion 9y of the cam JX with the hubot the gear i), thus engaging the clutch 1)". At theA sainel time theotl'set portion ly ot the cam l): will be brought into engagement withthe hub ol the gear l thus engaging the clutch ll). It will be readilyseen that the shaft l) will thus be driven at: low speed t'roin thedrive shaft S through the gears l and 2 and the gears and i). lt it isdesired to increase the speed ot rotation ot the driven sha't't l) fromlow to second speed, a movement ot the lever from the. notch "1" to thenotch 2" will result in a 'further rotation oil the camshaft', with theresultantY disengagement ot the clutch 5)" and the engagement ol theoll'set portion itl of the cam lo with the hub ot the gear 10, thusengaging the clutch 10'); the oll'set portion ly on the cam 1F being otsutlicient length to maintain the engagement of the clutch Il Ji'or bothlow and intermediate speeds. Movement ot' the lever from the notch 2" tothe notch il lor high speed will result in like manner in thedisengagement of the clutch lll", the caza ,nalt l( being 'furtherrotated until the otlset portion lil-l' ofi the cam lil-Y is broughtinto engagement with the hub ot the clutch incinber ll, thereby engagingthe clutch lil. itt the .same time the cam l.x will have been ro` tatedso as to bring thel straight portion thereot into engagement with thehub ot' the. gear l with the resultant disengagement ot This, as abovedescribed7 permits` of the tree, rotation ot the shaft S within the,gear l, and results in the direct drive ol the shatt l) ilirom thesha'lft S, all ot the gear coming to rest. lilith the lever ll at theneutral position, a movement thereof lrom the notch N to the notch Rwill result. in a rtwerse rotation o'l the cani shalit, in the directionoi:A the arrow, see Figurel 13, bringing the oll'set portion 115' ol'the cam llx into engagement with the hub portion ot' the lgear ll. thusengaging thel clutch lll. ,fit the same time. the oli'set portion l otthe cam l* will be brought, into engagement with the hub of the gear l,thus again engaging the clutch l". l`he sha'lft l) will thus be drivenat reverse spec'` irom the shat't, ,Si through the gears l and :2 andthe l`gears 8, l2, and l1. ll'ith the transmission in low, intermediateor reverse speeds, the clutch il) will be in engagement; as well aseither ot the clutches 5), lo or ll" in accordance with the speed orgearing desired. lilith the engine in high speed all ot' these clutcheswill be disengaged, only the high speed clutch lil" being in operat iveen ga gement.

lo insure the proper automatic operation of the engine clutch C, the CamC" is provided with ay plurality of oiset portions CY reversely directedwith respect to the otlset port-ions on the other cams. These offsetportions Cy are located or positioned in staggered relationship to thepositioning ot' the oiiset portions of the cams for controlling thevarious speeds. lt will thus be clearly understood from an examinationof .lfigure lo ot the drawings, that duringr the period ot shitting fromany speed to an other, one oi these offset portions Cf will be broughtinto engagement with the hub ot the clutch C with the resultant:disengagement oi' the said clutch during the shifting period.iiccordingly the engine clutch will be. automatically and graduallyshifted or properly let in and out with the variation o t the gear orspeed of rotation of the driven shalt. therebyv obviating thepossibility of an attempt to shift gears without the engine clutch beingproperly operated or disengaged and without the necessity of anyoperation other than the shifting of the gear shit't or control lever.All of the oll'set. portions on all oi" the earns are provided withgradually sloping sides thereby assuring the gradual eng:lgemcntj ordisengagement ot any particular clutch as desired.

lt will be noted that the shafts In' and l) are preferablyv square incross section and that the various gears are mounted on sleevespositioned on the said shafts, while the .stationary portions ot theclutches are mounted directly upon the square shafts. The lengths ollthe sleeves are such as to permit, them to positively contact with eachside of such stationary clutch members. thus retaining said membersimniovably positioned upon the shafts upon which they are mounted. Thereis thus provided a novel extremely economical and convenient method otmounting all ot the gears and clutchesl without. the use ot keys,screws, etc., permitting ol' the free rotation upon the sleeves ot theslidable halt ot' each clutch and at the same time insuring the rigiditywith which the stationary portions ol' such clutches are mounted. lVhilethe shafts l) and #i have been illustrated and described as beingpreferably square in cross section l'or the reasons above set torth7 itwill be obvious` that round or other types olI shafts might be employedwith the various parts properly mounted thereon.

There has thus been described a transmission wherein all of the gearsare constantly in mesh; wherein shifting otl gears may be readil/vaceomplisheffl without possibility of stripping of the gears and withoutthe dilliculty or necessity of considering the relative speed ot thevehicle with respect to the speed of rotation ot the engine shaft.;wherein the shitting or variation from a high to a lower gear may be asreadily and conveniently madehthus utilizing the increased braking powerot the engine at the lower speed when descending ffrades-as from a lowto a higher gear; and wherein change of gearing is had by a continuousmove.

ment of the gear shift or control lever in a single direction.

The invention having thus been described, what is claimed is v l. ln avariable speed transmission including driving mechanism and a' drivenshaft carrying a plurality of clutch Controiled transmission gears, acam shaft carrying a disk-like cam adapted to directly engage with oneof said clutches and aetuatc said clutch to engage the transmission gearwith the driving mechanism and means for operating said Cam.

2. A variable speed transmission comprising a clutch controlled driveshaft, a driven shaft, a clutch between said ldrive and driven shafts, aplurality of clutch controlled transmission gears slidably mounted forfree rotation on the driven shaft the said gears forming the slidableportions of such clutches, a counter shaft carrying a series of gearsmeshing with the said transmission gears and a clutch controlledoperative connection between the said drive yand counter shafts, a camshaft carrying a series of circular cams adapted to directly engagebetween shoulders formedl on the slidable portions of the clutchmechanism and operable to cause driving engagement of the transmissiongears with the driven shaft, and means for progressively operating saidcams, saidV means comprising a lever pivotally mounted within thetransmission housing carrying a toothed segment, a pinion secured to thecam shaft meshing with the said toothed segment whereby the cam shaftmay be progressively rotated to operatively engage the cams with theclutch mechanism.A

In testimony whereof he ai'lixes his signature.

ROSS H. PRATT.

